kfifo: move out spinlock
Move the pointer to the spinlock out of struct kfifo. Most users in
tree do not actually use a spinlock, so the few exceptions now have to
call kfifo_{get,put}_locked, which takes an extra argument to a
spinlock.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index c3f8d82..e0f5c9d 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -30,13 +30,12 @@
unsigned int size; /* the size of the allocated buffer */
unsigned int in; /* data is added at offset (in % size) */
unsigned int out; /* data is extracted from off. (out % size) */
- spinlock_t *lock; /* protects concurrent modifications */
};
extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer,
- unsigned int size, spinlock_t *lock);
+ unsigned int size);
extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
- gfp_t gfp_mask, spinlock_t *lock);
+ gfp_t gfp_mask);
extern void kfifo_free(struct kfifo *fifo);
extern unsigned int __kfifo_put(struct kfifo *fifo,
const unsigned char *buffer, unsigned int len);
@@ -58,58 +57,67 @@
*/
static inline void kfifo_reset(struct kfifo *fifo)
{
- unsigned long flags;
-
- spin_lock_irqsave(fifo->lock, flags);
-
__kfifo_reset(fifo);
-
- spin_unlock_irqrestore(fifo->lock, flags);
}
/**
- * kfifo_put - puts some data into the FIFO
+ * __kfifo_len - returns the number of bytes available in the FIFO
* @fifo: the fifo to be used.
- * @buffer: the data to be added.
- * @len: the length of the data to be added.
+ */
+static inline unsigned int __kfifo_len(struct kfifo *fifo)
+{
+ register unsigned int out;
+
+ out = fifo->out;
+ smp_rmb();
+ return fifo->in - out;
+}
+
+/**
+ * kfifo_put_locked - puts some data into the FIFO using a spinlock for locking
+ * @fifo: the fifo to be used.
+ * @from: the data to be added.
+ * @n: the length of the data to be added.
+ * @lock: pointer to the spinlock to use for locking.
*
- * This function copies at most @len bytes from the @buffer into
+ * This function copies at most @len bytes from the @from buffer into
* the FIFO depending on the free space, and returns the number of
* bytes copied.
*/
-static inline unsigned int kfifo_put(struct kfifo *fifo,
- const unsigned char *buffer, unsigned int len)
+static inline __must_check unsigned int kfifo_put_locked(struct kfifo *fifo,
+ const unsigned char *from, unsigned int n, spinlock_t *lock)
{
unsigned long flags;
unsigned int ret;
- spin_lock_irqsave(fifo->lock, flags);
+ spin_lock_irqsave(lock, flags);
- ret = __kfifo_put(fifo, buffer, len);
+ ret = __kfifo_put(fifo, from, n);
- spin_unlock_irqrestore(fifo->lock, flags);
+ spin_unlock_irqrestore(lock, flags);
return ret;
}
/**
- * kfifo_get - gets some data from the FIFO
+ * kfifo_get_locked - gets some data from the FIFO using a spinlock for locking
* @fifo: the fifo to be used.
- * @buffer: where the data must be copied.
- * @len: the size of the destination buffer.
+ * @to: where the data must be copied.
+ * @n: the size of the destination buffer.
+ * @lock: pointer to the spinlock to use for locking.
*
* This function copies at most @len bytes from the FIFO into the
- * @buffer and returns the number of copied bytes.
+ * @to buffer and returns the number of copied bytes.
*/
-static inline unsigned int kfifo_get(struct kfifo *fifo,
- unsigned char *buffer, unsigned int len)
+static inline __must_check unsigned int kfifo_get_locked(struct kfifo *fifo,
+ unsigned char *to, unsigned int n, spinlock_t *lock)
{
unsigned long flags;
unsigned int ret;
- spin_lock_irqsave(fifo->lock, flags);
+ spin_lock_irqsave(lock, flags);
- ret = __kfifo_get(fifo, buffer, len);
+ ret = __kfifo_get(fifo, to, n);
/*
* optimization: if the FIFO is empty, set the indices to 0
@@ -118,36 +126,18 @@
if (fifo->in == fifo->out)
fifo->in = fifo->out = 0;
- spin_unlock_irqrestore(fifo->lock, flags);
+ spin_unlock_irqrestore(lock, flags);
return ret;
}
/**
- * __kfifo_len - returns the number of bytes available in the FIFO, no locking version
- * @fifo: the fifo to be used.
- */
-static inline unsigned int __kfifo_len(struct kfifo *fifo)
-{
- return fifo->in - fifo->out;
-}
-
-/**
* kfifo_len - returns the number of bytes available in the FIFO
* @fifo: the fifo to be used.
*/
static inline unsigned int kfifo_len(struct kfifo *fifo)
{
- unsigned long flags;
- unsigned int ret;
-
- spin_lock_irqsave(fifo->lock, flags);
-
- ret = __kfifo_len(fifo);
-
- spin_unlock_irqrestore(fifo->lock, flags);
-
- return ret;
+ return __kfifo_len(fifo);
}
#endif